This invention relates to the use of splash bars in cooling towers and other direct-contact heat and mass transfer structures and particularly to an improved splash bar construction.
In general cooling towers include a large housing through which air is admitted and exhausted while at the same time water to be cooled is distributed throughout the housing by means of gravity and is cooled during its descent by its intimate contact with the air moving through the housing. During its descent the water is broken up into smaller droplets by contact with splash bars which break up the downward flow of the water and provide an increased surface area for commingling the water and air passing through the housing to promote cooling. As is well known, such cooling towers may be of the cross-flow type in which the air travels transversely to the descent of the water, or of the counter-flow type in which the air travels in a direction opposite to the descent of the water. The splash bars are horizontally stacked so that spaced-apart bars in each row are separate and staggered from bars in adjacent rows. To secure this arrangement, vertical and horizontal rod supports are provided upon which and against which the bars are secured by suitable clamps or other devices.
In particular, splash bars used in such cooling towers should be of such a configuration that optimum cooling is achieved by maximum liquid disbursement so that maximum splash is created from one bar to another, that is, the creation of the smallest droplets for maximizing a heat and mass transfer surface for the air passing through the tower.
This optimum condition--of the creation of small droplets--is often defeated by the use of splash bars which cannot maintain their horizontality in the cooling tower and thus create water-slide or a cascading effect along the accumulated slant of the bars, that is, an uninterrupted surface, especially a flat surface, along which the cascading effect of the water can form to thereby become an abosorbent film. In such cases, too, vibration of the bars can occur, owing to the cascading and accumulating effects of the water, such that the structural integrity of the bars is then weakened over time, often resulting in breakage.
In attempting to maintain strict horizontality of conventional splash bars, recourse is often had to the use of elaborate securing devices for fixing the bars to horizontal and vertical rod supports within the cooling tower. Such securing devices--often in the form of additional securing members, such as clamps, or adjunct structure associated with each bar assembly--require added time and expense to manufacture as well as additional time to install in the cooling tower.
In still other cases, splash bars are constructed from flat perforated sheet material for enhancing liquid break-up when the water moves from one surface to the next. In such cases the perforations in the sheet members--because of constant inundation from the water--are given to forming cracks along the edges of the holes which will eventually weaken the bars and cause breakage. In fact, splash bars of any given flat-surface design, regardless of the perforation or the hole design, will of necessity offer some form of a flat surface to the descending water and thereby augment not the formation of a splash effect, that is, the creation of droplets, but of the formation of a water film which will effectively absorb any surrounding splash. If larger holes are used in the sheet-type of splash bars then, of course, structural strength and integrity are sacrificed.